Check out this thread...

https://www.crossfireforum.org/forum...t=exhaust+tips

My response was:

A simple way to clean and keep your exhausts tip clean is to use soapy water and "lightly" rub out the black soot
with a SOS/Brillo pad and then dry. There is no need to buy brushes, bug/tar remover or carb cleaner and tape
off the tips.

To polish, use Never-Dull wadding polish as suggested in another post. To maintain the clean look, wipe out the tips
every month or so with a damp rag and spend a few minutes with the wadding polish.

It's an easy 30 minute job to clean them out the first time around, depending on how long you want to spend polishing
the tips. It takes even less time to maintain the look.